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ImageMagick is my/the goto for all batch processing of images. Open Source Cross Platform Using with the Linux find command, (Warning: This will invert in-place every image it finds): cd the_top_dir_of_your_image_tree find . -name "*.jpg" -exec magick mogrify -negate {}; Note that some versions of ImageMagick install convert and mogrify as distinct tools ...


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I'm surprized no one mentioned ImageMagick, it's the reference in command-line FOSS softwares for image edition, specially batch edition. It's cross-platform and present by default in many Linux distributions. Definitively a must.


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I like to use GIMP image editor. GIMP is a free, cross-platform image editor available for GNU/Linux, OS X, Windows and more operating systems. It has a toolbox full of useful tools for manipulating an image after you have rescaled it. Also useful with GIMP is another app named Simple Screen Ruler. This app displays a ruler on the screen. You can measure ...


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IrfanView is a free image-editing tool with a many batch-operation options, as shown below, and the JPEG save dialog includes the progressive option. It is a Windows application, but runs well under wine in Linux (and is available in a Snap port), so it might work in wine on MacOS, also. The only possible disadvantage is the large number of choices, but ...


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Your best option may be to recreate the image using a vector program such as Inkscape (free, multi-platform). Inkscape supports bitmap tracing, which will reduce the workload a bit. I've taken your tiny bitmap and ran it through the tracing and the results were not particular encouraging. It does a form of color separation, but that would require manual ...


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I suggest using GIMP. It's free open-source software. Use the magic wand tool to select the parts of the image you want to surround. Then Select > Grow, to add the width of the border (e.g., 4px). Then Select > Border (e.g., 4px), to create a border selection. Next, pick white as the color you want to use with the fill tool (the bucket) that you can fill ...


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An oldie question, but I'll add my 2 cents to it. I am guessing you need some sort of "exam type" stuff, where it randomly selects some images and you need to answer what they are. I would make a custom script made in PHP and run it locally. The program would need to: Read the names of all images from a designated folder. Randomize the name list. ...


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If you are happy with python and have PIL or Pillow installed then the answers to https://stackoverflow.com/questions/2498875/how-to-invert-colors-of-image-with-pil-python-imaging is a way to go. You can add in a glob to find all of your images. Something like: from PIL import Image from PIL import ImageOps from glob import glob import os os.chdir('...


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Turns out, ffmpeg can handle this too! In particular, I found this page: https://ffmpeg.org/ffmpeg-filters.html#eq. Using the eq filter, one can modify contract, brightness, saturation, gamma, r, g, b, and more.


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The FFmpeg showwavespic filter can produce an image of the waveform of an audio input and has a few parameters to customize the output. Here's an example invocation (from the above link) : ffmpeg -i audio.flac -lavfi showwavespic=split_channels=1:s=1024x800 waveform.png Example output: More examples and documentation: https://trac.ffmpeg.org/wiki/...


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JDeli can read/write WebP format and many others, but it isn't free.


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I found these online services that do offer online GIF compression including a deduplication in frames: https://www.iloveimg.com/compress-image (Does not explicitly advertise this deduplication, but I checked the resulting GIFs.) https://compress-or-die.com/gif (Just to provide an alternative. Their max upload file size is 16MB which was too low for me so ...


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